Note: Salesforce has a standard VLOOKUP function but has limited functionality, this approach helps overcome those without code.

Process Builder and Flows are recent automation engines provided by Salesforce, they have been around for a while but haven't been used widely i believe (probably developers tend to stick with Apex Triggers and Workflow rules as they are used to it)

The use case below shows you how you could use these two together to solve a simple scenario which as a developer we tend to solve with Apex Code.

Scenario:

Everytime a Product2 record is updated, i have to query if this product exists in a custom object (Exempted parts) and based on the result update a boolean field on Product2.

Solution:

STEP 1:

Create a Flow (Product2_Validate_Exemption)

STEP 2:

Create a Process and call the flow every time a product2 record is updated.